New protocols that started in FY16: 1. 15-DK-0192: Quantifying the Persistence of Metabolic Adaptation and Weight Regain Following Extreme Weight Loss. PI Kevin Hall, PhD. ClinicalTrials.gov Identifier: NCT02544009. 2. 15-DK-0119: Thyroid Hormone to Induce Non-Insulin Mediated Glucose Disposal in People With Insulin Receptor Mutations PI. Rebecca Brown, MD. ClinicalTrials.gov Identifier: NCT02457897. 3. 16-I-0078: Microbial, Immune, and Metabolic Perturbations by Antibiotics (mime study). PIs. Steven Holland, Martin Blaser. ClinicalTrials.gov Identifier: NCT02707042 Research highlights: 1. We published four papers with Dr. Jack Yanovskis research group. The body composition and fitness measures we provided for the protocol Mood and Insulin Resistance in Adolescents At-Risk for Diabetes (11-CH-0239, NCT 01425905) were critical to show the effects of treatment in overweight adolescent girls at risk for type 2 diabetes. From another ongoing study (13-CH-0169 NCT01888939), we studied the effects of interrupting sedentary behavior on metabolic outcomes in children. In this paper, we found that, by interrupting sedentary time with brief moderate-intensity walking improved short-term metabolic function in non-overweight children without increasing subsequent energy intake. These findings suggest that interrupting sedentary behavior may be a promising prevention strategy for reducing cardiometabolic risk in children. We are now working on the same protocol in overweight and obese children. 2. We continue to explore and make discoveries from the unique dataset that we collaborated with Icelandic Heart Association and NIA from 2008-2010, and produced two papers in FY16. In a cohort of community-dwelling healthy older adult Icelandic volunteers (average age 80), we found that while day length and activity both had a significant influence on the pattern of sleep timing, the actual within-individual differences of the repeaters were rather subtle between periods of longer and shorter day-lengths. We conclude that the limited variation in sleep patterns and quality in response to significant changes in daylight may be due to long-term adaptation in these aging subjects. Moreover, we found in another paper that, objectively measured activity and sedentary parameters late in life are associated with current and prior cross-sectional measures of brain atrophy, and the changes over time. Together, these conclusions highlight the power of using objective measures of physical activity, sleep, and sedentary behavior in free-living populations. 3. We also worked with other accelerometer datasets from the US NHANES and one from Brazil, with the goals to improve our abilities to explore the impacts physical activity and sedentary behavior may have on our health. We published three papers on these topics. 4. New studies are being planned with collaborations with intramural and extramural collaborators. In FY 16, Dr. Rebecca Brown started a new study that uses the metabolic chamber to evaluate the effects of thyroid hormone on glucose and energy metabolism in patients with insulin receptor mutations. Brown fat will also be quantified using our established protocols and analyses techniques. We also successfully competed in an intra-extramural U01 grant titled Microbial, immune, metabolic perturbations by antibiotics (MIME study) (NIH 1U01AI22285-01, PI. Martin Blaser) with investigators from NYU and NIAID. We will study the effects of two common antibiotics a tetracycline (doxycycline) and a beta-lactam (amoxicillin) on human microbial populations and on metabolic and immune physiology in healthy volunteers in three aims: (1) the effects of a brief therapeutic course of antibiotics on microbiota and metagenome composition, (2) the effects on immune functions, and (3) the effects on metabolic physiology (24-hr metabolic chamber studies at 5 time points). 5. The Core continues to support 21 clinical protocols and protocols from 5 different IC's of the NIH. Services rendered (FY16 activities): energy expenditure by whole-room respiratory chambers (338), resting energy expenditure by metabolic carts (201), graded-exercise tests (78), experimental food behavior tests (182), and body composition (266 DXA, 71 Bod Pod).